One- to Three-Dimensional Crossover in the Lattice Dynamics ofHg3−δAsF6: Low-Temperature Specific Heat

Abstract

The temperature dependence (0.35 K to 6 K) of the low-temperature specific heat of the linear chain mercury compound, ${\mathrm{Hg}}_{3-\delta }\mathrm{As}{\mathrm{F}}_6$ is reported. The one- to three-dimensional crossover in the low-temperature lattice specific heat due to the phase-ordered incommensurate Hg chains is observed. The results are analyzed with use of Tarasov's phenomenological theory for the specific heat of the weakly interacting one-dimensional chains. The specific-heat results yield a value for the phason mode energy, $\frac{\Delta }{k_{\mathrm{B}}}=1.75\mathrm{}$ K.